This invention relates to compounding, and glazing or polishing pads which are used to finish/refinish exposed paint surfaces on automobiles (particularly with regard to the paint type called basecoat/clearcoat, but as not to exclude other types of paint) as well as other products. These pads are of the type that are releasably attached to a back up pad which is rotated by a drive motor (commonly referred to as a buffing machine or polisher), which operates at a typical speed in the range of 1,000-3,000 R.P.M.
In the steps of the paint finishing/refinishing process, whether it is new paint, or paint that has been exposed to the elements (weathered), sanding with fine grit abrasive (e.g., 600-2000 grit) is sometimes necessary to level the surface or remove imperfections. This sanding process leaves scratches in the paint surface. Typically, lambswool or open cell foam compounding pads are used to apply compound to remove surface scratches caused by sanding. Foam compounding pads generally are comprised of polymeric reticulated open cell flexible polyester urethane foam with open cells of approximately 50 P.P.I. (pores per inch). After the compounding process, typically there are still finer scratches in the paint surface. These scratches are generally referred to as swirl (or wheel) marks. Typically, the final step of the process is to go over these scratches with a less abrasive or non-abrasive glazing compound applied with either a finer lambswool pad or a foam polishing or glazing pad. These foam polishing or glazing pads generally are comprised of polymeric reticulated open cell flexible polyester urethane foam with open cells of approximately 80 P.P.I.
Two basic types of foam pads with different front surfaces are commonly in use (the front surface referring to the surface of the pad which actually comes in contact with the surface to be polished). One type has a front surface that is generally planar (e.g., Refer to U.S. Pat. No. 3,418,675). This type of pad is herein after referred to as a "traditional flat pad". The other type has a front surface that has a similar appearance to an "egg crate" design (e.g., Refer to U.S. Pat. Nos. 4,962,562, 5,007,128, 5,185,964, 5,396,737, and Re. 35,021). This type of pad is herein after referred to as a "convoluted pad". Both of these pads are of the type that are rotated by a drive motor, at a typical speed in the range of 1,000-3,000 R.P.M.
In a trial referred to in U.S. Pat. Nos. 4,962,562, 5,007,128, 5,185,964, 5,396,737, and Re. 35,021, whereby test panels were painted with black paint of the basecoat/clearcoat type, and when "Imperial", a machine glaze available from Minnesota Mining and Manufacturing Company, "3M", of St. Paul, Minn., was used, and whereby the performance of the "traditional flat pad" was evaluated for the purpose of removing wheel marks, the results of said trial reflected "long working time apparently because of low absorbency of the foam pads. Also, such foam pads have the tendency to sling glaze onto the adjacent area which may have already been finished. Build up of dried glaze on the surface of the foam pad can be deposited on the paint surface, resulting in a smear on that surface; and when the painted surface is almost dry and the final gloss is near, such foam pads have the tendency to grab the paint surface which causes vibration or chatter and operator fatigue".
In a trial (such as described in the immediately preceding paragraph) test results were produced using a traditional flat type pad of the type described in U.S. Pat. No. 3,418,675, and using a convoluted foam pad of the type described in U.S. Pat. No. 4,962,562, and Re. 35,021; using a machine glaze, and using test panels coated with black paint of the basecoat/clearcoat type. Results of the trial of the traditional flat pads were similar to the results reflected in the immediately preceding paragraph, with the exception of the "long working time", which was apparently not due to the low absorbency of the pad, but most likely due to the build up of debris in the center area of the pad. Apparently this build up of debris (comprised of removed paint, compound, particles of foam from the pad, and other foreign substances which may have been on the surface of the paint) caused additional friction and heat, resulting in smearing, vibration or chatter, and necessitated additional time being spent to complete the task. The results of the trial using the convoluted pads also presented limitations, including long working time, a tendency to sling glaze on adjacent areas, and a build up of debris on the elevated surfaces of the foam projections. Apparently, this build up of debris created additional friction and heat resulting in smearing. Also, with respect to the convoluted pad, another limitation noted was durability. When the convoluted pad surface is new, there is already a greatly reduced working surface area in comparison to the full surface of traditional flat pads (with the convoluted pad, it is just the ends of the projections that provide the working surface). During the course of the trial, several of the foam projecting portions of the convoluted pads wore off during use, creating even less of a working surface left on the pad. When this occurred, smearing increased dramatically, which ended the pad's useful life, significantly sooner than traditional flat pads.